1. Field of the Invention
This invention relates to a miniature video camera means adapted for use in video systems and more particularly to a small, compact video camera head having a housing which is substantially the same size as a vidicon tube and yoke and which includes circuit means for preamplifying and driving a coaxial cable in a direct wire television system with an amplified video signal.
2. Description of the Prior Art
A video camera head for a closed circuit television system is disclosed in U.S. Pat. No. 4,028,730 to Frederick A. Miller, inventor of the invention described herein and having a common assignee.
The video camera head described in U.S. Pat. No. 4,028,730 is a small compact, lightweight, color video camera and includes a vidicon tube and two printed circuit boards, one of which is positioned between the opening of the metal housing and the vidicon tube and the other of which is located between the rear of the videcon tube and the housing. Due to the electrical components required in order to drive the coaxial cable utilized in a direct wire closed circuit television system with an amplified electrical video signal, a first printed circuit board is utilized for the preamplifying means for producing an amplified, video signal which is then applied to the second printed circuit board located at the opposite end of the housing wherein the electrical video signal is amplified by an amplifying means and applied to an emitter-follower amplifier means to drive a coaxial cable with an amplified electrical video signal.
Recently, use of color video cameras and closed circuit television systems have experienced great expansion in the medical and related fields. As such, it is becoming imperative that the size of the video camera head be reduced so that it can be readily attached to medical optical devices, microscopes and the like. In surgery, components maintained within the sterile field of operation must, of necessity, be reduced to the minimum possible size.
As the size of the known video imaging means is reduced, it becomes more difficult to recover the video signal produced from the video imaging means. It is desirable for the electrical video signals to have a signal to noise ratio of more than forty (40) decibels.
Thus, the length of electrical conductors which extend from printed circuit boards in the video camera head and the capacitive effect thereof results in additional noise into the electrical video signal which reduces the signal to noise ratio of the electrical video signal in the associated television systems.